Benthic diatoms as indicators of herbicide toxicity in rivers – A new SPEcies At Risk (SPEARherbicides) index. (April 2019)

• Record Type: Journal Article
• Authors: Wood, Rebecca J.; Mitrovic, Simon M.; Lim, Richard P.; Warne, Michael St. J.; Dunlop, Jason; Kefford, Ben J.
• Is Part Of: Ecological indicators. Volume 99(2019)
• Page Start: 203
• Page End: 213
• Publication Date: 2019-04
• Subjects: Traits -- Biomonitoring -- Herbicide tolerance -- Diatoms -- Field effects; Environmental monitoring -- Periodicals; Environmental management -- Periodicals; Environmental impact analysis -- Periodicals; Environmental risk assessment -- Periodicals; Sustainable development -- Periodicals; 333.71405
• DOI: 10.1016/j.ecolind.2018.12.035
• Languages: English
• ISSNs: 1470-160X

Abstract

Highlights: A new index developed using diatom traits to indicate agricultural herbicide impacts. The SPEARherbicides index negatively correlates with herbicides, nutrients and TSS. The Diatom community recovered during the dry season from herbicide effects. Herbicide sensitive diatoms declined with increased grazing and cropping in catchment. Abstract: Benthic diatom communities are used widely as indicators of river health due to their rapid response to changes in water quality. The ability for diatom-based indices to detect eutrophication has been well documented; however, an index designed specifically to detect herbicide impacts is yet to be established. This is required as herbicide contamination of rivers is common in agricultural regions and poses a potential threat to aquatic ecosystems. This study developed a new biomonitoring index (SPEARherbicides ) using benthic diatom communities to detect the toxic impacts of herbicides in rivers, and tested it across 14 rivers in the Great Barrier Reef catchment area, Australia. The new index uses diatom species traits to classify diatoms as either sensitive or tolerant to herbicides and calculates the fraction of sensitive taxa within a sample. The SPEARherbicides index showed a decline in herbicide sensitive diatoms with increasing herbicide toxicity of the sites. The impacts of herbicide toxicity on the diatom community were only apparent after the wet season when aqueous herbicide concentrations typically peak and diatoms were able to recover during the dry season when herbicide concentrations were lower. SPEARherbicides values had a negative relationship with the percentage of grazing and cropping in catchments but had a positive relationship with the percentage of conservation in catchments. SPEARherbicides also had a negative relationship with co-occurring potential stressors such as nutrients and total suspended solids.